Newbie questions on 10k spindle alignment

palada

palada

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Jul 30, 2022
Messages
33
Hi all,

I'm completely new to machining, so keep that in mind when I ask silly questions or make false assumptions please.

I bought a 1950s SB 10k at an estate sale this year. Because the previous owner was deceased and I couldn't get history on it, I picked up a guide to renovation on eBay and disassembled it to clean it and replace felts. I followed the manual closely for disassembly and reassembly. It's back together now and everything works.

The problem is that I think the spindle is too far out of true. With a dial test indicator on the flange, I get a variance of .0085 when I turn the spindle. When I put a piece of small round stock in the chuck, I get .0055. As mentioned, I'm no expert, but this seems like a lot to me, even for hobby stuff.

Some questions: this is too much variance, right? Anyone know the cause/solution? Seems like the spindle would have to be egg shaped to measure that way. If it is egg shaped, can it be remediated? Thanks in advance for educating me.

spindle.jpg
 
Likely there needs to be an adjustment of the thrust bearing on the far end of the spindle.
 
That flange is just that a flange, has no effect on the chuck.
You could have .050 there and not have an issue.
 
benmychree said:
Likely there needs to be an adjustment of the thrust bearing on the far end of the spindle.
Click to expand...
Do you mean the bearing with separate races? How would I adjust that? I don’t find google results for that. or do you mean the nut with the fiber washer? I tightened that until I felt drag on the spindle, then backed off 1/12 turn as my book said.
 
Jim F said:
That flange is just that a flange, has no effect on the chuck.
You could have .050 there and not have an issue.
Click to expand...
There’s still .0055 on a bar in the chuck. isn’t that still a lot?
 
Are you talking end play of the spindle? In other words, movement along the axis of rotation.

Or are you talking about run-out of the spindle perpendicular to the axis of rotation?

From the picture it looks like you are set up to measure end play. IF that is the case I would think the thrust bearing nut at the far end of the spindle is your only adjustment. Since you had it apart, were you able to determine the condition of the thrust bearings as good or did you replace them with new? Since I have not had my 10K apart to this level yet, I can't give any advice other that what is in your book. (I have that book too). You may need to tighten the thrust bearing nut a smidgen to get rid of the end play. A little pre-load on the bearing probably won't hurt it. On the other hand if the bearings are bad, it could show up as an end play problem no matter how tight the bearings are.

In either case I don't think I would rely on the trueness of the flange as a final authority of the either end play or run-out. Putting something in the chuck and turning it, then measuring might be a better way to measure? I'm not sure but it would seem if the lathe will turn within listed tolerances you should be good to go.
 
Just an idea that popped into my head for checking end play.
Chuck up something that is maybe 2" in diameter. It doesn't have to be very long, any old scrap will do. Face it off and then put a center hole in it for tail stock support. Set up your indicator and measure for end play on the new face. Then put the tail support in place and put a little pressure on the piece and measure as you apply preasure. You could take readings near the center and near the edge of the face. Mark any high or low spots and see if that translates across the entire face.

I'm not sure what all this would give you but at least you will have eliminated the flange as a possible source of readout error.
 
You must log in or register to reply here.
Back
Top